"What feels different between a person doing something with ki and the same person doing the same something without ki? What is your qualitative experience of ki?"

When a person has mind and body co-ordinated (has ki) and they are throwing me it feels like they are tuned in and blending with me.,..they take my balance subtly and they cause me to fall with out man handling me. If someone is throwing me and thinking about what it looks like or what they are going to do they lose connection, they rely on muscle energy and often lose their own balance.

I can see if a person has ki by that person's posture, by the speed of the throw in relation to how uke is moving, by their uke's response, by how they feel when I am testing them for one point, by the expression on their face,...I guess the real answer is by how they look and feel and how they move.